The invention relates to an improved fuel cell stack assembly.
Fuel cell stack assemblies are typically a plurality of fuel cell components arranged in a stack and held together by pressure plates. FIG. 1 shows a typical conventional fuel cell stack assembly, and shows a single fuel cell component 1 in a center portion of the stack including a cathode water transfer plate (WTP) 1a and an anode and cooler plate 1b. On either side of this component are unitized electrode assemblies (UEA) 2, and this sequence is repeated through the stack until the end plate assembly 3 which, in conventional fuel cell assemblies, requires a unique water transfer plate and a non-porous graphite plate 4. End/pressure plates 5 are as shown. The end-plate water transfer plate interface further features coolant channels bonded by the non-porous graphite plate 4.
This configuration poses several problems, including additional cost and design complexity due to the unique components required for the end of the stack. Further, the non-porous graphite bonded to the WTP causes additional structural complexity since this material has a different modulus than the remainder of the repeating components. Further, corrosion protection complexity at the current collector interface is increased due to having an unknown environment near the current collector. Due to the solid graphite plate, it is never clear whether the environment is hydrogen, air or water.
It is clear that the need remains for improved fuel cell assembly structures to address the aforesaid problems.
It is therefore the primary object of the present invention to provide an improved fuel cell stack assembly wherein unique end cell assemblies are avoided.
It is a further object of the invention to provide such an assembly wherein the environment adjacent to the current collector is known.
Other objects and advantages of the present invention will appear hereinbelow.